FIELD OF THE INVENTION
The present invention relates to an image processing apparatus and, more particularly, to an image processing apparatus for extracting a floor region and an obstacle region from an image taken by a camera.
In medical and welfare facilities such as hospitals and nursing homes, there is a demand for the development of robots (self-propelled carriage, automatic guided vehicle, autonomous mobile robot, etc.) which automatically carry meals, washing, etc. There is also a demand for the development of self-propelled carriages used in office buildings, schools, factories, etc. and on the road or the like.
When a robot works, it is necessary to detect an obstacle in its travel range. As a method of detecting an obstacle, detection methods using an ultrasonic sensor, an optical range sensor or the like have conventionally been proposed. These methods, however, suffer from the following problems. Since a distance is measured by the ultrasonic wave or light reflected from an object, some attitude of the surface of an object or some reflection characteristic of an object makes the measurement of a distance impossible. In addition, an ultrasonic sensor has a poor spatial resolution. On the other hand, in the case of using an optical range sensor, since a wide range is measured with a high accuracy, it is necessary to use a high-output laser, which causes an apprehension as to the safety.
In contrast, there is provided a method of detecting an obstacle from an image taken by a camera. According to this method, a part in which there is a large change in the density is extracted from the image as an obstacle. Therefore, this method is free from the above-described problems of an ultrasonic sensor or an optical range sensor.
In a conventional detection method using an image taken by a camera, however, since a part in which there is a large change in the density is extracted from an image, such a large amount of computation is necessary that it is impossible to extract an obstacle in a short time.